Dozens of workers were pulled out of the Arkema Inc. plant before the hurricane hit, and a small crew of 11 that had been left behind was evacuated before the blasts for fear of just such a disaster. Officials had also ordered people living within 1? miles (2.4 kilometers) to leave on Tuesday.

Fire and plant officials said the substances that caught fire were organic peroxides, a family of volatile compounds used for making a variety of products, including pharmaceuticals and construction materials.

Earlier this week, French-owned Arkema warned an explosion was imminent at the plant about 25 miles (40 kilometers) northeast of Houston, saying Harvey’s floodwaters had knocked out power and backup generators, disabling the refrigeration needed to keep the organic peroxides stable.

On Thursday, Rich Rennard, an executive at Arkema, said the chemical compounds were transferred to refrigerated containers after power was lost. But he said those containers failed too, causing the chemicals in one unit to burn.

He said the company expected more explosions from the eight remaining containers.

The plant is along a stretch near Houston that contains one of the biggest concentrations of refineries, pipelines and chemical plants in the country. Houston is the nation’s fourth-largest city, with a population of 2.3 million.

Andrea Morrow, a spokeswoman for the Texas Commission on Environmental Quality, said the agency had not received any reports of trouble at other chemical plants in the hurricane-stricken zone.

The blaze at Arkema sent up 30- to 40-foot (9- to 12-meter) flames and black smoke, according to fire officials. Harris County Fire Marshal spokeswoman Rachel Moreno put the quantity of burning organic peroxide at 2 tons.

Sheriff Ed Gonzalez said some of his deputies suffered eye irritation from the smoke and 15 sought medical attention.

The EPA sent employees to monitor the situation and said air samples collected by…